#define _CRT_SECURE_NO_WARNINGS 1
/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};*/
class Partition {
public:
    ListNode* partition(ListNode* pHead, int x) {
        struct ListNode* head1, * head2, * tail1, * tail2;
        head1 = tail1 = (struct ListNode*)malloc(sizeof(struct ListNode));
        head2 = tail2 = (struct ListNode*)malloc(sizeof(struct ListNode));
        struct ListNode* cur = pHead;
        while (cur) {
            if (cur->val < x) {
                tail1->next = cur;
                tail1 = tail1->next;
            }
            else {
                tail2->next = cur;
                tail2 = tail2->next;
            }
            cur = cur->next;
        }
        tail1->next = head2->next;
        tail2->next = NULL;
        pHead = head1->next;
        free(head1);
        free(head2);
        return pHead;
    }
};